Dogs have evolved 'face reading' skills to detect if their owner is happy or sad

It will come as no surprise to dog lovers, but man's best friend is remarkably good at detecting our moods.

A study has shown that dogs look for signs of anger, irritation or happiness in faces in exactly the same way that people do.

Scientists believe dogs have evolved their 'face reading' skills over thousands of generations as a way of avoiding an unwelcome kick.

They say that dogs deal differently with human faces from any other image, and that their method of processing the information is the same as humans use.

Past studies have shown that human faces are lop-sided when it comes to showing emotion.

Moods such as anger, pleasure and fright are expressed far more clearly on the right side of our faces than on the left.

Researchers say the right side of a face is more expressive because it is controlled by the left hemisphere of the brain, which deals with emotions.

When most people meet a stranger face on, their gaze tends to shift to the left and they watch the right side of the unfamiliar face. The phenomenon - known as 'left gaze bias' - has been shown time after time in experiments.

Now a team led by Dr Kun Guo from the University of Lincoln have found that dogs show the same preference, New Scientist magazine reports.

Happy days: Scientists say dogs can tell when people are happy or angry (file picture)

The researchers showed images of people, dogs, monkeys and inanimate objects to 17 pets and filmed the animals' head and eye movements.

When the dogs looked at pictures of animals, their eyes flicked evenly across the image. But when they were presented with human faces they tended to gaze to the left, just as people do.

Dr Guo said the bias evolved in domestic dogs to help them gauge human emotions. They do not deal with animal faces in the same way because these are less important in expressing emotion.

A second study found that dogs have a much stronger bias to the left when looking at angry faces rather than happy or neutral ones.

The discovery suggests it is far more important for dogs to gauge a human's mood quickly and accurately when a person is angry, and therefore possibly violent.